All mobile equipement carries an unique IMEI number (Internation Mobile Equipement Identity), which can be used in all sorts of ways, including remotely shutting down the device and rendering it useless.

The shop you bought the phone from (and the network provider) will have a record of this number, and if the phone was purchased on contract that can be traced to you. If it wasn't bought on contract then I suspect the trail will go cold at the shop who stocked that particular device.

Again, unless the SIM card was part of a contract agreement there wouldn't be any way to tie it back to the original purchaser.

Even if you registered a PAYG SIM with the provider that does nothing to prove who bought it, only who registered it.

You may have some luck if you still have the phone box and SIM carrier (the plastic sheet you snap the SIM card out of) as these both carry the unique numbers also printed on the SIM and device, so with the help of proof of purchase you could prove you bought that device and SIM, but that's a long shot and requires you to gain access to the SIM and device again.

Just some thoughts.

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